1. Field of the Invention
The present invention relates to complexes of clay and polyoxyalkylene amine grafted polypropylene copolymers and a method for producing the same, the complexes in which can be particularly applied to oily surfactants and reinforcing agents of polymers.
2. Description of the Related Technology
Currently, inorganic/organic polymer composite materials under a nanoscale regime are one of the most significant materials, and thus have been widely investigated and developed. Such composite materials are dual-phased wherein at least one phase is dispersed under a nanoscale regime. Accordingly, compatibility between the two phases, for example, clay and polymers, is always essential for the nanoscale dispersion.
For layered silicate clay which is hydrophilic and immiscible with most organic solvents, the interspace is looser when intercalating with organic quaternary ammonium, and thus monomers are allowed to enter therethrough. The monomers can be polymerized to obtain an exfoliated inorganic/organic polymer composite material. In principle, the distances, enlarged by intercalating agents, are constant and required to be wide enough for monomer or polymer molecules to enter. As for exfoliation, the interlayer distances are irregular and different directions may occur in each silicate platelet. Therefore, the stack of layered silicates is no longer in an ordered form but dispersed in organic polymers with in individual platelet. The exposed surfaces are tremendously increased and the silicates/organic polymers interaction order magnitude enhanced.
Conventional intercalating agents such as 12-aminolauric acid, hexadecylamine, fatty alkyl amine, bis(2-hydroxyethyl) methyl tallow alkyl ammonium chloride and stearylamine, usually commercially available surfactants having low molecular weights, and interlayer distances of the clay can be expanded to a certain degree.
Referring to the research of T. J. Pinnavaia (Michigan State University), intercalating agent CH3(CH2)nxe2x80x94NH3+ is provided to mixed with montmorillonite (MMT), which is then dispersed in diglycidyl ether of BPA (epoxy resin Epon828) to form a polyether-clay composite material under a nanoscale regime. For such intercalating agent, the interlayer distances can be enlarged to 18.0 xc3x85. The epoxy resin can then form an epoxy/clay material through self polymerization at 75xc2x0 C. This reference also indicates an improvement in heat distortion temperature. The intercalating agent performs a rule of monolayer to bilayer, and even to pseudo-trilayer. The interlayer distance ranges between 13.8-18.0 xc3x85, which allow the epoxy resin to enter and polymerize therein, and further to exfoliate the layered inorganic matter so that application effect including mechanical property of inorganic/organic nanomaterials can be achieved.
Japanese Patent No. 8-22946 discloses the first commercial inorganic/organic polymer composite material under a nanoscale regime, which is developed by Toyota Company. This composite material is produced by dispersing [H3N+(CH2)11COOxe2x88x92]-montmorillonite in Nylon 6 polyamide, wherein the aminocarboxylic acid is provided as an intercalating agent and the polymers are formed between layers of the clay through condensation of caprolactam monomers. However, the aminocarboxylic acid doesn""t facilitate nonpolar polymers such as polyethylene and polypropylene, to uniformily disperse in the hydrophilic layered silicate. Accordingly, Japanese Patent Publication No. 8-53572 provides organic onium ions as an intercalating agent to mix with layered silicate, which can be uniformly dispersed in molten polyolefin resin. Unfortunately, though the organic onium ions can enlarge the interlayer distances, affinity between the intercalating agent and the polyolefin resin is not enough to exfoliate the layered silicate. Further, Japanese Patent Publication No. 10-182892 indicates that when blending in a molten mixture containing olefin oligomers with H-bond and polyolefin resin, the organized layered silicate might be indefinitely exfoliated due to the strong affinity therebetween. However, it""s a dilemma whether to increase the oligomers for better dispersing or to decrease the oligomers for better mechanical characteristics. Hence, the main problem to be overcome is the lacking of compatibility between hydrophilic inorganic silicates and hydrophobic or nonpopolar organic polymers.
Accordingly, there is a need to ameliorate the composites by means of providing appropriate intercalating agents which can act as compatibilizers, so that the silicates can be modified and complexed to become as novel inorganic/organic surfactants. The complexes can be used as such to be surfactants which have wide and important industrial applications. Furthermore, the intercalated complexes can be further used to compound with other nonpolar organic polymers such as polypropylene, polyethylene, polybutylene, etc. as the conventional nanomaterials are required.
The object of the present invention is to provide a complex of clay and specific intercalating agents and a method for producing the same, so that the complex is stable enough and has excellent affinity for polymers and organic matters. The specific intercalating agents are polyoxyalkylene amine grafted polypropylene which is possessing both ionic amine intercalating ability and polypropylene backbone hydrophobicity.
In order to achieve the above object, the more specific complex of the present invention is primarily formed by modifying inorganic layered silicate clay with an amphibious intercalating agent obtained by polymerizing polyoxyalkylene amine having molecular weight over 1,800 and polypropylene-grafting-maleic anhydride (PP-g-MA). The polyoxyalkylene amine grafted PP-g-MA is the product from the reaction of amines and maleic anhydride to form amidoacid or imide linkaged graft copolymer.
The polyoxyalkylene amine aforementioned can be polyoxyalkylene diamine, and preferably polyoxypropylene diamine, polyoxyethylene diamine, poly(oxyethylene-oxypropylene) diamine and polyoxypropylene triamine.
The layered silicate clay used in the present invention is not restricted, and preferably montmorillonite, kaolin, mica or talc. In general, the clay with CEC (cation exchange capacity) ranging between 50-200 meq/100 g is preferred. Beyond such a range, the clay is difficult to be swelled because of insufficient ion exchange or excessive attraction between layers.
The method for producing the complexes of the present invention is primarily to polymerize the polyoxyalkylene amine having molecular weight over 1,800 and polypropylene-grafting-maleic anhydride (PP-g-MA) to form an amphibious intercalating agent. The intercalating agent is then acidified with an inorganic acid, and then mixed with the swelled clay by powerfully stirring at 60-80xc2x0 C. for cation exchanging to obtain the complex.
The inorganic acid aforementioned is not restricted, and preferably hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid.
According to the present invention, the complexes of clay and PP-g-MA grafted polyoxyalkylene amine are hydrophobic, rather than hydrophilic as before the intercalation, and compatible with polymers. The complexes can be applied as oily surfactants and be used to improve characteristics of polymers.